Push nipple



June 30, 1953 w. J. DUNN 2,643,646

PUSH NIPPLE Filed Aug. 18, 1948 6 10 id y E I S if 42 7 5 l fi 6 I UH? 17 6.1; I wewr & Z%C --f-- Patented June 30, 1953 PUSH NIPPLE 7 William J. Dunn, Westfield, Mass, assignor to The H. B. Smith Company, Incorporated, Westfield, Mass, a corporation of Massachusetts Application August 18, 1948, SerialNo. 44,928

This invention pertains to fluid-tight receptacles of sectional type, for instance but without limitation, heat exchange apparatus such as radiators (for heating or cooling), steam generators, water or other fluid heaters, refrigerators, tills, etc., and more particularly to an improved push nipple for uniting adjacent sections of said apparatus. While of utility for uniting adjacent sections of apparatus of specifically different character, as above suggested, I

it is here illustrated and described with particular reference to its use in uniting the sections of a cast iron boiler.

In the manufacture of push-nipple cast 'iron boilers, a common practice is to ream one or more tapered holes or nipple ports in the fire side of the front section and in the fire side of the rear section and to provide the intermediate or leg sections with conically tapered ports at corresponding points at each side of each section.

When the sections are assembled otherwise, as is sometimes done, the arrangement of the holes or nipple ports is correspondingly varied. In the assembly of such a boiler, a prior practice has been to use conically tapered pushnipples of cast iron, malleable iron, steel, brass, etc., and of such diameter as to fit snugly into the aforesaid tapered ports, and to use draw-up bolts to pull the section together so as to bring the nipples into intimate contact with the walls of the ports and thus to provide a continuous fluid passage through the several sections of the boiler, so that the boiler becomes a leak-proof receptacle or container within the limits of the fluid pressurefor which it is designed. The usual prior push nipple is a short, tubular part, commonly of approximately uniform internal diameter, but tapering at its outside from a midsection of maximum diameter toward its opposite ends, respectively, the tapering surface usually being a right conical surface extending from the midsection to the extreme end of the nipple. Since the tapering portions of the nipples are of substantial length and have substantially the .same taper as the port and are designed to fit tightly in the ports, it is necessary to apply very substantial force'in assembling the sections in order to draw the nipples far enough into the ports to insure a tight joint. Moreover, since the nipple does not usually enter very far into the port when first introduced, it is necessary to move the adjacent sections toward each other a substantial distance to seat the nipples in the final position, and this requires that the nuts of the pull-up bolts be given a good many turns, which makes assembly slow 8 Claims. g (01. 122-231) and laborious. When using such nipples it is sometimes impossible, even by the application of force great enough to stretch the bolts or strip their threads, to draw the parts into leak-tight contact since the presence of chips, dirt, or even slight irregularities at the extended meeting surfaces of nipple and port wall may result in crevices which no amount of tightening will close.

Moreover, since the usual nipple can not always be firmly wedged by hand into the port in the section, difficulty inassembling the section is often experienced because the nipples tend to fallout of one section before the next section can be put in place. The present invention has as one object the provision of an improved push nipple so designed as greatly to reduce the time required 7 for assembly of the sections, as compared with usual prior practice; to provide a leak-tight joint without necessitating the application of so great a force in drawing the sections together as is usual; to provide a nipple having a relatively small contact surface for engagement with the walls of the ports in the sections so that the unit pressure at the contact area is great as compared with that which is obtainable in usual constructions, thu helping to insure a leak-tight joint; to provide a nipple so designed as to minimize the possibility that the nipples will fall out during assembly, thus facilitating the operation and reducing costs; and to provide a nipple which is simple in construction, easy to manufacture and light in weight.

'A further object is to providea nipple of such design that the boiler sections may be drawn together into leak-tight union by the application of force whose intensity is less than that which might cause injury to the sections.

A further object is to provide a nipple having a pilot portion at each end which is easily entered into the port in the boiler section and which is of a length such that the nipple is held in place during the assembly of adjacent sections without tendency to dropout.

A further object is to provide a nipple having its effective contact surface or surfaces located adjacent to it midportion' and of such contour as to provide a narrow area of contact with the wall of the port in the boiler section.

Other and further objects and advantages of the invention will be pointed out in the following more detailed description and by reference to the accompanying drawings wherein:

Fig. l is a'fragmentary vertical section, longitudinally of a boiler of the sectional type and 'to a narrow band, for

3 substantially at the center of the boiler, showin the sections united by nipples according to the present invention;

Fig. 2 is a horizontal section, to much larger scale than that of Fig. 1, showing portions of two adjacent sections of the boiler united by a nipple according to the present invention, the section being in the horizontal 'diametri'c plane of the nipp Fig. 3 is a fragmentary vertical section, approximately to the same scale as Fig. 2, showing a boiler section with its axially aligned tapering nipple-ports;

Fig. .4 is a diametric section of a nipple embodying the present invention;

Fig. is an end view of the improved nipple; and

Fig. 6 is a plan view of the nipple.

Merely by way of explanation and as an example of its utility, but without limiting intent, the invention is here illustrated as embodied in a sectional boiler comprising the front section I (Fig. l), the rear section 2, and a plurality of intermediate or leg sections 3. As more clearly illustrated in Fig. 3, each of these midsections is provided with axially aligned nipple ports 4 which taper inwardly in diameter, the fire side only of the front and rear sections being provided with such ports. The taper of these ports may vary, but a taper of inch per foot of axial length is cited as an example of an appropriate taper. The walls 5 of the ports are usually of right conical contour.

The improved push nipple of the present invention is indicated at 6 (Fig. 4). One or more of these nipples is interposed between each pair of adjacent sections so as collectively to provide continuous passages for steam or water or both through the bank of sections. -As illustrated in Figs. 2 and 4, but without limiting intent, the nipple 6 is of uniform internal diameter, having the cylindrical inner surface I. The end or pilot portions 8 and 9 of the nipple are preferably of uniform external diameter, the end portions thus being cylindrical. However, these end surfaces need not be truly cylindrical, for example, they may be slightly tapering, or slightly curved, the maximum external diameter, in any case, being less than that which would cause the end or pilot portion to contact the wall of the port when the nipple is in operative position. That portion of the nipple which lies substantially midway between its ends is of an external diameter greater than that of the end or pilot portions 8 and-9. The outer peripheral surface of this midportion ill is here illustrated, in longitudinal section, as convex, preferably with a circular curvature with the center of curvature on a diameter P-Q (Fig. 4) midway between ends of the nipple, so that the arc of curvature is symmetrical with respect to the ends of the nipple. As illustrated in Fig. 4, the arcuate surface ll intersects the cylindrical surfaces of parts Band 9 at the lines 12 and 13, respectively. While as illustrated, and for conveniencein manufacture, the curved surface is uninterrupted between the lines l2 and I3, the exact midportion of the peripheral surface might be cylindrical, concave or of other contour, since the exact midportion does not contact the port walls. Since the surface H "or at least each end portion thereof is curved while the port wall is conical, contact between the surfaces is limited theoretically to a geometric line, but, practically,

from to A wide. It appears by experiment example, of the order of v that the radius of curvature of the surface H should be approximately three inches for secur ing the desired results. A radius of the order of three inches provides a desirable slope of the nipple surface at the point of contact, and provides good frictional retention when the nipple is first inserted in the .port. It has also been found that a chordal length, axially of the nipple, of approximately one inch between the lines 12 and 13 (Fig. 6) gives good results, although it is to be understood that the exact dimensions thus suggested may be varied to some extent without departing from the invention. The maximum diameter of the surface II is somewhat greater than the maximum diameter of the port, and the diameter of the nipple at the lines l2 and i3 is somewhat less than the minimum diameter of the port. For illustration, the maximum diameter of the nipple may exceed that of the port by 0.275 inch. Depending upon exact relative dimensionsin any given case, the narrow contact band maybe substantially spaced from the plane of maximum diameter of the port, or may be located'very close to said plane, but as illustrated, will usually be located well within that half of the length of the port where the port is of maximum diameter.

This provision for spacing the contact 'a'rea from the large end of the port is of value since the port wall is sometimes chipped 'or nicked at its extreme outer end. When the contact'are'a is spaced inwardly from the end of the port the damaged wall is avoided and a closefit is assured.

The maximum outside diameter of the substantially cylindrical end or pilot portions 8 and 9 of the nipple is slightly less than the minimum diameter of the port '4 in the boiler section with which the nipple is to be used, so that the cylindrical pilot portion of the nipple may be slipped freely into the port for some distance before there is any binding contact between the nipple and the wall of the port. For example, the external diameter of the cylindrical pilot portion of the nipple may be of the order of 0.006 inch less than the minimum diameter of the port, so that there is enough clearance '(Fig. 2) between the port wall and the cylindrical end portion of the nipple to insure an easy sliding fit when the parts are being assembled. Thus, in assembling the nipple with the boiler sections, the pilot portion of the nipple may easily be inserted into the port in one boiler section, entering well into the port, and, since the initial contact between the surface H and the port wall is of very limited area, the nipple may be pushed quite readily by hand into the port until the nipple binds sufliciently to retain it in place while the next section is being assembled with the first. Thus, the work of assembly is much facilitated and there is little danger that the nipple will fall out of the .port after once having been placed therein. Merely by way of example of desirable dimensions, the nipple may be of such axial length that the distance between the end of the nipple andthe line 1-2 or the line [3 would be from 1 to T% of an inch, dependent upon the diameter of the nipple. I When the nipple is inserted, a part of its convex surface contacts the wall of the port, and, since the surface It is curved while the wall-5 of the por-tis a conical surface, the-contact between the nipple andthe wall in theory, at least, approaches a true line contact. Thus when the bolts, the pressure at this narrow contact area out cutting or upsetting) and so eliminate any possible crevices due, for example, to scratches, defects or injuries to the meeting surfaces, thus insuring a leak-tight union between the parts. From examination of nipples which have been removed, after having been assembled with boiler sections, it appears that the actual area of contact, resultant from such deformation of the contact surface, is a narrow, peripheral band of the order of from to in width. This condition results even though the force applied in drawing the sections together be substantially less than that necessary when using nipples of usual prior types in which the contact surfaces between the nipple and port walls are of large extent. Moreover, as above pointed out, the initial deep entry of the nipple into the port permits the adjacent sections to be assembled closely even before the pull-up nuts are tightened, so that but few turns of the nuts are required in completing the leak-tight assembly, thus saving substantially in the time and expense of assembling.

In assembling the sections, the substantially cylindrical end portions of the nipples act as pilots to guide the nipples accurately into the ports and to prevent cocking during assembly, while the curved contact surface of the nipple acts, as the parts are drawn together, something like a ball joint to facilitate the approach of the parts.

As pointed out above, the push nipple of the present invention, while primarily designed for use in connecting adjacent sections of the usual sectional heating boiler, is equally applicable for the connection of adjacent sections of any sectional heating exchange apparatus such, for instance, as a heating radiator, wherein the sections have conically tapered ports for the reception of the connecting nipples.

Moreover, while cast iron is specifically referred to as the material from which the nipple and boiler section is made, it is to be understood that cast iron is thus referred to merely because it is the customary material now employed in making the sections of a heating boiler and without limiting intent as to the specific chemical analysis of the material employed, the principal feature being that the nipple shall have the characteristic rigidity and lack of resiliency or pliability of ordinary cast iron.

While one desirable embodiment of the invention has been illustrated and described by Way of example with specific dimensions suggested as useful and desirable, it is to be understood that the invention is broadly inclusive of all modifications and embodiments which fall within the scope of the appended claims.

I claim:

l. A cast iron sectional boiler comprisingsections and connecting push nipples, adjacent sections having axially aligned, conically tapered ports for the reception of the ends of the push nipples, each nipple having an axial bore of substantially uniform diameter, the peripheral surface of the nipple at opposite sides of its transverse mid-plane being convexly curved in longitudinal section, the diameter of each convexly curved portion progressively increasing toward said midplane, the minimum diameter of each convexly curved portion being less than the di- 6 ameter of the larger end of the port, and the maximum diameter of each convexly curved portion being greater than the diameter of the larger end of the port, the nipple having a pilot portion at each end of a diameter slightly less than the diameter of the smaller end of the port.

2. A cast iron sectional boiler comprising sections and connecting push nipples, adjacent sections having axially aligned, conically tapered ports for the reception of the ends of the push nipples, each push nipple being of a diameter at its transverse mid-plane which exceeds the maximum diameter of the port, each end portion of the nipple being cylindrical and of an external diameter sufliciently less than the minimum diameter of the port to permit said end portion to be entered into the larger end of the port a limited distance before the nipple engages the port wall, the peripheral surface of the nipple at each side of its transverse mid-plane being convexly curved in longitudinal section, the diameter of each convexly curved portion progressively increasing toward said mid-plane and the slope of the convexly curved surface being such that when the parts are assembled theconvexly curved surface contacts the conical wall of the port adjacent to but spaced inwardly from the larger end of the port.

3. A cast iron sectional boiler comprising sections and connecting push nipples, adjacent sections having axially aligned, conically tapered ports for the reception of the opposite ends respectively of the push nipples, each end of each push nipple having a pilot portion which is of substantially uniform diameter and a length of from approximately T e to of an inch, said diameter being slightly less than that of the smaller end of the port thereby to permit said pilot portion of the nipple to enter the larger end of the port with a free fit, the outer peripheral surface of the nipple intermediate its pilot portions comprising parts which are convexly curved in longitudinal section, the diameter of each of said convexly curved parts progressively increasing from a diameter equalling that of the pilot portion of the nipple to a diameter which exceeds that of the larger end of the port.

4. A cast iron sectional boiler comprising sections and connecting push nipples, adjacent sections having axially aligned, conically tapered ports for the reception of the respective ends of the push nipples, each nipple being of the order of 1 /5; inches in axial length, each end of the nipple constituting a pilot member of a substantially uniform diameter approximately 0.006 inch less than that of the smaller end of the port, the external peripheral surface of the nipple at each side of its transverse mid-plane being convexly curved in longitudinal section, the diameter of each convexly curved portion progressively increasing toward said mid-plane, the minimum diameter of each convexly curved portion substantially equalling that of the pilot members of the nipple, and its maximum diameter exceeding that of the larger end of the port.

5. A cast iron sectional boiler comprising sections and connecting push nipples, adjacent sections having axially aligned, conically tapered ports for the reception of the respective ends of the push nipples, each push nipple being of the order of 1 inches in axial length and at its midplane exceeding the maximum diameter of the port by approximately 0.0275 inch, each end portion of the nipple being of a substantially uniform external diameter slightly less than the minimum 7 diameter of the port whereby said end portion is easily insertable within the larger end of the port a limited distance before the nipple engages the port wall, the external peripheral surface of the nipple at each side of its mid-plane being convexly curved .in longitudinal section, each such convexly curved portion of the nipple progressively increasing in diameter toward said midplane, the slope of each said convexly curved portion being such that when in use the area of contact between said convexly curved portion and the conical wall of the port is spaced from the larger end of the port.

6. In a sectional cast iron boiler whose adjacent sections have conventional conically tapered, axially aligned ports for the reception of push nipples, in combination, a rigid cast iron push nipple having its opposite ends disposed within the aligned ports of adjacent sections, the maximum external diameter of the central portion of the nipple being such that the operative contact between nipple and port walls is confined to narrow bands within the larger end portions of the respective ports, those portions of the external peripheral surface of the nipple which lie at each side respectively of its mid-length being convex in longitudinal section and making contact with the wall of the port in the corresponding section along a peripheral band not substantially exceeding /4 inch in width, the nipple having end portions which are externally substantially cylindrical and of an external diameter sufficiently less than the minimum diameter of the ports to provide a clearance of the order of 0.003 inch between the end portions of the nipple and the port wall, whereby the end portions of the nipple are initially insertable within the larger end of the port a limited distance before the convex surface of the nipple engages the port wall.

'7. In combination, two adjacent cast iron boiler sections having axially aligned ports in their walls and a rigid cast iron push nipple having its end portions disposed within the respective ports and which provides leak-tight communication between the interiors of the two sections, the wall of each port being a right-conical surface, tapering inwardly from the outer surface of the section, the push nipple having a cylindrical pilot portion at each end, the outside diameter of the pilot portion being slightly less than the diam- :eter of the small end of the port whereby said pilot portion may be slid freely into the port but is kept in substantial axial alignment with the port,

the nipple being of uniform internal diameter but having a central portion whose outside surface is convex in longitudinal section, the maximum diameter of said convex portion being greater than the diameter of the larger end of the port and the minimum diameter of said convex portion being less than the maximum diameter of the port, the curved outer surface of the nipple engaging the conical wall of the port along an annular contact bandnot substantially exceeding one-quarter inch in axial width and which is spaced inwardly from the outer surface of the section and whose axis is substantially perpendicular to the axis of the port.

'8. In combination, a pair of cast iron boiler sections having axially aligned ports in their walls and a rigid cast iron push nipple providing a leak-tight connection between the interiors of the sections, the wall of each port being a rightconical surface tapering from the outside of the section inwardly, the nipple being of uniform internal diameter and having end portions which fit with sliding clearance in the smaller ends of the respective ports, the nipple having exterior contact surf-aces intermediate said end portions which engage the conical walls of the respective ports, each saidcontact surface of the nipple being convex in longitudinal section and engaging theconical wall of the respective port only along a circular contact band not substantially exceeding one-quarter inch in width, said band being coaxial with the port and spaced inwardly from the larger-end of the port.

WILLIAM J. DUNN.

References Cited .in the file of this patent UNITED STATES PATENTS Number Name Date 689,986 Phelps Dec. 31, 1901 1,188,485 Pruyn June 27, 1916 1351500 Vincent Aug. 31, 1920 1,631,911 Brahm June '7, 1927 1,666,566 Hawley Apr. 1'7, 1928 1,810,825 Furrer Jan. 16, 1931 1,883,925 Hyde Oct, 25, 1932 1,987,341 Kac'hel Jan. 8, 1935 2,011,433 Blagg et al Aug. 13, .1935 2,125,324 Williams .et al. Aug. 2, 1938 FOREIGN PATENTS Number Country 'Date 17,023 Great Britain Dec. 30, 1884 

